Process of concentrating ores by flotation



UNITED- STATES PATENT OFFICE.

BARNETT L. GEORGE, OF SALT LAKE CITY, UTAH.

PROCESS OF CONCENTRATING ORES BY FLOTATION.

No Drawing.

the flotation process which is now carried out by subjecting the orepulp to sub-aeration or to agitation in contact with air, after addingto the pulp a quantity of oil or other suitable frothing agent, with orwithout the addition of an acid such as sulfuric acid, whereby a mineralbearing froth is formed which may be floated off. The present inventionis based upon the discovery that the flotation process isimproved by theaddition to the ore pu llp of a quantity of zinc sulfate (ZnSO heimprovement is particularly marked when the zinc sulfate is used inconjunction with oils which give an organic acid reaction, althoughimproved results are obtained when the reagent is used with oil givingan alkaline reaction.

The invention comprises the use of zinc sulfate with various grades andkinds of oils, but the use of this reagent is especially advantageous inconjunction with light oils of crude coal tar, such as Barrett No. 4'

creosote oil. This particular oil formerly gave an alkaline reaction,and this alkalinity, though not enough to precipitate the tar acids,appeared to protect the oil from the acid in the pulp mixture, wherebythe oil was capable of being more readily emulsified. The more recentoutput of Barrett No. 4 oil gives an organic acid reaction and resistsemulsification to a greater extent than the alkaline oil. The BarrettNo. 4 oil of alkaline reaction gives excellent results in conjunctionwith sulfuric acid, but the newer oil of acid reaction when used in theflotation process gives a tailing having a metallic content from 20% to50% higher than that obtained when the corresponding alkaline oil isused. When this Barrett No. 4 oil having an organic acid reaction isused Without sulfuric acid, a tailing is obtained which is comparablewith that obtained by the use of the alkaline oil, but .it is found thatthe froth builds up in the flotation ma- Specification of LettersPatent.

Patented Apr. 26, 1921.

Application filed August 9, 191 8. Serial No. 249,059.

chine and fails to discharge over the spitzkasten. The use of sulfuricacid provides the aeration necessary for the discharge of the froth, butif used with the oil having an acid reaction, it ruins the selectiveproperties of the oil, and the selective properties of the oil of acidreaction when used with sulfuric acid have thus far not been improved byrendering alkaline the oil which gives the acid reaction.

However, I havefound that zinc sulfate possesses the property of givingimproved results when used either with an alkaline oil or an organicacid oil, such as the old Barrett No. 4 and the new Barrett No. 4 oil,for example. Zinc sulfate is quite soluble in water and when introducedinto the flotation machine as a solution it can be easily handled. It iscomparatively cheap and compares favorably with sulfuric acid in costper ton of ore feedtreated; it hasthe advantage over sulfuric acid thatit gives an increase in the extraction of from 10% to 30%. Zinc sulfatepossesses no selective properties in itself, but it performs thefunction of sulfuric acid with improved results and with none of theinjurious effects which the latter has upon the flotation machine.

In carrying out the process, the finely ground ore is mixed with waterto form a freely flowing pulp, and to this pulp there is added a smallquantity of oil, such as Barrett No. 4 oil forexample, together with asmall quantity of zinc sulfate. The zinc sulfate is preferably added inthe proportion of from three to six pounds for each ton of dry ore feedtreated, and the zinc sulfate solution may be added to the pulp mixturein the flotation machine. The mixture of pulp, oil, and zinc sulfate soformed is then subjected to a flotation operation, in which the mixtureis agitated and aerated to produce a froth which may be floated oil fromthe spitzkasten or other separation vessel. A thorough emulsification ofthe zinc sulfate, oil, and pulp, is necessary to procure the mostsatisfactory results. The quantity of zinc sulfate to be used forobtaining the best results Will depend to some extent upon the method ofcarrying out the flotation operation and upon the nature of the orebeing treated;

The following example shows the comparative results following the use ofBarrett No. 4 oil of the organic acid and the alka- Cu. rougher tails.Alkaline Barrett No. 4 oil with sulfuric acid .O9 Alkaline Barrett No. 4oil with zinc sulfate .100 Acid Barrett N0. 4 oil and sulfuric acid .420Acid Barrett No. 4 oil and zinc sulfate .120

The foregoing example shows that zinc sulfate gives results with theacid 011 nearly as good as those obtained w1th the alkaline oil, andboth of these results are comparable to the results obtained with thealkaline 01]. and sulfuric acid, and very much better than. the resultsobtained with organic acid oil and sulfuric acid. i

It has been found further that when zinc sulfate is used as a reagent inthe flotation process, the results are particularly. improved whentreating ores which. do not readily yield to separation by flotation.The following is an example ofthe results obtained by the use of zincsulfate as compared with sulfuric acid when treatlng a difficult copperore feed:

Cu. rougher tails. Alkaline Barrett No. 4 oil and sulfuric acid 430fllitlfifi 3233? it). i tiltilt fitttiiiitai'aaaria;

crude oil Zinc sulfate as a reagent in the flotation process appears towork substantially equally well with both the alkaline oil and theorganic acid 011, and can be used beneficially withthe organic acid Oll,such as the new Barrett No. 4 oil, when sulfuric acid cannot. It gives-agood extraction on an ore feed which is difficult to treat in caseswhere it has been found that the alkaline oil and sulfuric acid do notgive a good extraction. It has further been found that when zinc sulfateis used with a mixture of crude mineral oil and coal tar oil, the frothis tender, well mineralized, and lively, whereas, when sulfuric acid isused with these oils, there is a tendency to produce a similar conditionof froth but the selective properties are comparatively poor.

Although I have described a particular method of carrying out myimproved process and have given specific examples by way ofillustration, it will be understood that the process may be altered invarious ways without departing from the scope of the invention asdefined by theappended claims.

What I claim is:

1. The process of concentrating ores, which comprises adding to anorepulp an oil having an organic acid reaction and a quantity of zincsulfate, and then subjecting the resulting mixture to a flotationoperation.

2. The process of concentrating ores,

which comprises adding to an ore pulp a quantity of light oil ofcrudecoal tar having an acid reaction and a quantity of zinc sulfate,and then subjecting the resulting mixture to a flotation operation.

3. The process of concentrating ores comprising adding to an ore pulpfrom three to six pounds of light oil of crude coal tar having an acidreaction for each ton of dry ore feed, and then subjecting the resultingmixture to a. floating operation.

4. The process of concentrating ores, which comprises mixing the finelyground ore with water to form a pulp, adding to the pulp a quantity oflight coal tar oil having an acid reaction and a quantity of zincsulfate, subjecting the mixture so formed to agitation and aeration, andseparating the froth produced by the aeration of the mixture.

In testimony whereof, I have subscribed my name.

I BARNETT L. GEORGE.

